Your inventory will roll over to your mailbox when full.

If you get 1000/1000 items/guardians, any additional drops you get will go to your mailbox under the "Expiry" tab.

They expire 3 days after you get them.

This "Expiry" tab can hold 10 items per page, and I'm currently at 3 pages -- so it's at least that big.

whycantiholdalltheseKOrbs.jpg
themoreyouknow.jpg